首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   3578篇
  免费   87篇
  国内免费   15篇
化学   2192篇
晶体学   15篇
力学   197篇
数学   760篇
物理学   516篇
  2023年   19篇
  2022年   52篇
  2021年   99篇
  2020年   75篇
  2019年   52篇
  2018年   65篇
  2017年   57篇
  2016年   112篇
  2015年   105篇
  2014年   83篇
  2013年   191篇
  2012年   208篇
  2011年   247篇
  2010年   145篇
  2009年   121篇
  2008年   204篇
  2007年   221篇
  2006年   165篇
  2005年   158篇
  2004年   146篇
  2003年   117篇
  2002年   99篇
  2001年   43篇
  2000年   26篇
  1999年   37篇
  1998年   36篇
  1997年   35篇
  1996年   36篇
  1995年   26篇
  1994年   30篇
  1993年   48篇
  1992年   19篇
  1991年   27篇
  1990年   29篇
  1989年   17篇
  1988年   26篇
  1987年   22篇
  1986年   24篇
  1985年   46篇
  1984年   44篇
  1983年   24篇
  1982年   25篇
  1981年   30篇
  1980年   28篇
  1979年   22篇
  1978年   26篇
  1977年   23篇
  1976年   23篇
  1975年   13篇
  1974年   21篇
排序方式: 共有3680条查询结果,搜索用时 8 毫秒
981.
Foundations of Computational Mathematics - We show that the algebraic boundaries of the regions of real binary forms with fixed typical rank are always unions of dual varieties to suitable...  相似文献   
982.
Journal of Algebraic Combinatorics - The sets of the absolute points of (possibly degenerate) polarities of a projective space are well known. The sets of the absolute points of (possibly...  相似文献   
983.
Nonlinear Dynamics - A novel statistical linearization technique is developed for determining approximately the response statistics and the power output of U-Oscillating Water Column (U-OWC) energy...  相似文献   
984.
Islet amyloid polypeptide (IAPP) is a hormone co-secreted with insulin and zinc from pancreatic β-cells. To overcome the low solubility of human IAPP, we characterized zinc complexes species formed with 1) a mutated form of rat-IAPP(1–37; R18 H) able to mimic the human IAPP, 2) the r-IAPP(1–37) and the IAPP(1–8) fragment. Stoichiometry, speciation and coordination features of zinc(II) complexes were unveiled by ESI-MS, potentiometry and NMR measurements combined with DFT and free-energy simulations. Mononuclear species start to form around pH 6; Zn2+ binds both His18 and N-amino terminus in rat-IAPP(1–37; R18 H). The in silico study allows us to assess not only a structured turn compact domain in r-IAPP(1–37) and r-IAPP(1–37; R18 H) featured by a different free energy barrier for the transition from the compact to elongated conformation upon the coordination of Zn2+, but also to bring into light a coordination shell further stabilized by noncovalent interactions.  相似文献   
985.
986.
Monatshefte für Mathematik - If G is an uncountable group of regular cardinality $$aleph $$, we shall denote by $${mathfrak {L}L}_aleph (G)$$ the set of all subgroups of G of cardinality...  相似文献   
987.
Potential Analysis - Let $mathbb {P}$ and $widetilde {mathbb {P}}$ be the laws of two discrete-time stochastic processes defined on the sequence space $S^{mathbb N}$, where S is a finite set of...  相似文献   
988.
Journal of Statistical Physics - We consider vectors of random variables, obtained by restricting the length of the nodal set of Berry’s random wave model to a finite collection of (possibly...  相似文献   
989.
Journal of Solution Chemistry - A study of the effects induced by a weak magnetic field of about 0.4 T on the precipitation of insoluble alkaline earth carbonates is reported. Optical...  相似文献   
990.
Truffles are underground edible fungi that grow symbiotically with plant roots. They have been globally considered as one of the most expensive foods because of their rarity, unique aroma, and high nutritional value as antioxidant, anti-inflammatory, antiviral, hepatoprotective, anti-mutagenic, antituberculoid immunomodulatory, antitumor, antimicrobial, and aphrodisiac. The unique flavor and fragrance of truffles is one of the main reasons to get worldwide attraction as a food product. So, the aim of this review was to summarize the relevant literature with particular attention to the active aroma components as well as the various sample preparation and analytical techniques used to identify them. The major analytical methods used for the determination of volatile organic compounds (VOC) in truffles are gas chromatography (GC), proton-transfer-reaction mass spectrometry (PTR-MS), and electronic nose sensing (EN). In addition, factors influencing truffle aroma are also highlighted. For this reason, this review can be considered a good reference for research concerning aroma profiles of different species of truffles to deepen the knowledge about a complex odor of various truffles.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号